title: Mutual effects of Pb(II) and humic acid adsorption on multiwalled carbon nanotubes/polyacrylamide composites from aqueous solutions.
abstract: This paper examines the adsorption of Pb(II) and a natural organic macromolecular compound (humic acid, HA) on polyacrylamide (PAAM) -grafted multiwalled carbon nanotubes (denoted as MWCNTs/PAAM), prepared by an N(2)-plasma-induced grafting technique. The mutual effects of HA/Pb(II) on Pb(II) and HA adsorption on MWCNTs/PAAM, as well as the effects of pH, ionic strength, HA/Pb(II) concentrations, and the addition sequences of HA/Pb(II) were investigated. The results indicated that Pb(II) and HA adsorption were strongly dependent on pH and ionic strength. The presence of HA led to a strong increase in Pb(II) adsorption at low pH and a decrease at high pH, whereas the presence of Pb(II) led to an increase in HA adsorption. The adsorbed HA contributed to modification of adsorbent surface properties and partial complexation of Pb(II) with the adsorbed HA. Different effects of HA/Pb(II) concentrations and addition sequences on Pb(II) and HA adsorption were observed, indicating different adsorption mechanisms. After adsorption of HA on MWCNTs/PAAM, the adsorption capacity for Pb(II) was enhanced at pH 5.0; the adsorption capacity for HA was also enhanced after Pb(II) adsorption on MWCNTs/PAAM. These results are important for estimating and optimizing the removal of metal ions and organic substances by use of MWCNT/PAAM composites.
authors.affiliation: Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences , Post Office Box 1126, Hefei 230031, People's Republic of China.
authors.forename: Shubin
authors.initials: S
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Changlun
authors.initials: C
authors.lastname: Chen
authors.forename: Dadong
authors.initials: D
authors.lastname: Shao
authors.forename: Xiangke
authors.initials: X
authors.lastname: Wang
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000327:Adsorption; D006812:Humic Substances / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D009994:Osmolar Concentration; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D006812:Humic Substances; D007854:Lead; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical; D000099166:Polyacrylamides